1. Field of the Invention
The present invention relates to an improved process for producing an electromagnetic radiation-shielding, metallized polyester fiber textile material containing polyester fibers. More particularly, the present invention relates to an improved and highly efficient process for metallizing a textile material containing polyester fibers by firmly fixing a metal coating thereto.
The electromagnetic radiation-shielded textile material containing polyester fibers metallized in accordance with the process of the present invention exhibits an excellent electroconductivity and is useful for shielding electronic devices from interference caused by electromagnetic radiation.
2. Description of the Related Art
Various processes are known for producing an electroconductive textile material by non-electrolytically plating a non-conductive textile material to metallize the material.
For example, Japanese Unexamined Patent Publication (Kokai) No. 54-55700 discloses a process for metallizing a textile material with a metal by immersing a textile material containing, for example, polyacrylonitrile fibers, in an acid aqueous colloidal palladium solution containing stannous ions, by activation-treatment of the palladium and tin (II)-impregnated textile material with an acid or alkali aqueous solution, and then by non-electrolytically plating the activation-treated textile material in an alkali solution of a compound of the metal.
Further, Japanese Examined Patent Publication (Kokoku) Nos. 40-27400, 46-22919, 49-43518 and 49-43519 disclose a process for metallizing a textile material with a metal by activation-treatment of a textile material with an aqueous solution of palladium chloride or stannous chloride, or by activation-treatment of the textile material with a stannous chloride aqueous solution and with a palladium chloride aqueous solution, and then, by non-electrolytically plating the activation-treated textile material with the metal.
However, a problem of the known processes is that when these processes are applied to a textile material containing polyester fibers, the resultant metallized textile material exhibits an unsatisfactory electroconductivity and uneven quality.
To eliminate the above-mentioned problem, attempts have been made to apply a pre-etching treatment with an acid or alkali to a textile material containing polyester fibers before the metallizing process.
For example, Japanese Examined Patent Publication (Kokoku) Nos. 46-22919, 49-43518 and 49-43519 disclose a pre-etching treatment of the polyester fiber textile material with an aqueous solution of 80 g/l of sodium hydroxide at a temperature of 50.degree. C. for one hour, or with an aqueous solution of 100 g/l of sodium hydroxide at a temperature of 60.degree. C. for 30 minutes, or with an aqueous solution of 1 g/l of sodium hydroxide and 4 g/l of lauryldimethylbenzyl ammonium chloride at a temperature of 80.degree. C. for 60 minutes.
The above-mentioned pre-etching processes have had a slight effect toward improving the metallizing property of the polyester fiber textile material, but are not very satisfactory.
Furthermore, it is known that the purity of the metal coating provided on the textile material by the conventional non-electrolytical plating process is unsatisfactory and that the crystallinity of the plated metal coating is insufficient, and therefore, the electroconductivity of the metallized textile material is unsatisfactory.